Negative electron affinity (Si-Na2KSb-Cs)-O-Cs photocathode

The work function of a silicon substrate will decrease rapidly and a negative electron affinity Si photocathode may be produced when a clean Si(100) substrate is activated by applying cesium and then oxygen, only once. But the work function of thus produced Si(100) photocathode would be increased and its integral photoemission sensitivity would be decreased if the cathode is subsequently treated with Cs and/or O2. In this letter, a new activation technology is adopted, and a reflection mode negative electron affinity (Si-Na2KSb-Cs)-O-Cs photocathode with maximum photoemission sensitivity S=2000 μA/lm is fabricated. The surface layer model and the energy-band structure of the photocathode are also discussed.